This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-345577, filed Nov. 13, 2000, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a contactor used to test an object to be tested for its electric characteristics, a method for manufacturing the contactor, and a probe card using the contactor.
2. Description of the Related Art
To test the electric characteristics of many subjects to be tested, for example, IC chips such as memory devices or logic devices formed on a semiconductor wafer (hereinafter called xe2x80x9cwaferxe2x80x9d simply), a probe card having a contactor can be used. In testing, by contacting the contact terminals (probe needles) of the contactor of the probe card to the corresponding electrode pads of the IC chip, the IC chip can be electrically connected to a tester. By this connection, a testing signal can be received and transmitted between the two. The contact terminals of the contactor of this probe card may be, for example, probe needles made of tungsten.
Recently, with the ever increasing integration density of an IC chip, its electrode pads have rapidly become numerous, shrunk in size, and narrowed in pitch. Since the probe needles made of tungsten employed in a probe card are made manually, its manufacturing costs increase and its delivery time limit is prolonged in proportion to the number of the pins used.
To meet a demand for reduction in the testing costs, there has been commercially available such a multi-chip contactor that enables simultaneous measurement of a plurality of IC chips. For example, there is a case where the number of contact terminals of the contactor for testing a logic device exceeds 2000. In the case of testing a memory device, there is a demand for increasing the number of devices to be measured simultaneously from 32 to 64. From this viewpoint, it is expected that the number of the contactor pins exceeds 5000 in the near future. As the pad size has decreased, it has been more and more difficult to manufacture the probe card.
The necessity of reserving a proper needle pressure for a probe card using tungsten-made needles limits the shortening of the needles. This is due to the Young""s modulus, assembly, etc. Since the length of the needles has an influence on the high-frequency characteristics of a high-speed device, there may be a fear that expected test results cannot be obtained.
To manufacture the contactor properly, there have been developed various technologies such as photolithography, etching, sputtering, plating, and other film forming technologies. Such a contactor is comprised of a contact terminal of, for example, a pyramid shape, a beam member supporting the contact terminal at its tip, a post supporting the beam member at its base end, and a board connected through the post. This contactor eliminates problems of a tungsten-made needle. Such a contact has a cantilever type structure in which the probe itself is fixed to the post. The contact terminal, the beam member, and the post of the probe are formed by their respective processes and undergo mechanical connection between the contact terminal and the beam member, that between the beam member and the post, and that between the post and the board by use of a means of, for example, transferring a wax material.
By a prior art method of manufacturing a contactor, its contact terminals, beam members, and posts are formed by different processes and then connected and unified. As a result, failure is liable to occur at the connection, leading to a problem of a lowered yield. Furthermore, this prior art suffers from many limitations; for example, the melting points of various wax materials used at the connection at a plurality of positions must be changed properly.
For example, Jpn. Pat. Appln. KOKAI Publication No. 8-50146 discloses a contactor having a structure utilizing, as a buckling space, a groove formed in a lower part of the beam member (probe) having a contact terminal. Jpn. Pat. Appln. KOKAI Publication No. 11-133062 discloses a structure in which a post (supporting portion) is provided to reserve the buckling space of the beam member (lead portion) having the contact terminal. Such a probe card is disclosed that has a structure in which the beam member is connected on this post. In the former case, the contact terminal is comprised of a silicon core and a plurality of conductive films coating the core. Although the beam member can be formed at the same time as the conductive films of the contact terminal, the formation of the contact terminal and the beam member requires a plurality of processes. Since the beam member and the board are further interconnected through a different lead wire, the number of connections increases, thus resulting in an increased contact resistance at the connections. In the latter case, a process is required to form the post besides a process for forming the beam member and also the beam member is disposed on the board through the post, thus resulting in an increased contact resistance at the connection.
The present invention solves at least one of the above-mentioned problems. One feature of one aspect of the present invention enables simplifying the processes of forming the contact terminal and the beam member. Another feature of another aspect of the present invention enables obtaining a contactor with an improved reliability of the structure. A further feature of another aspect of the present invention enables providing a contactor which improves the high-frequency characteristics and enables conducting reliable testing, a probe card using the same, and a method for manufacturing the same. An additional feature of another aspect of the present invention enables providing a probe card which enables surely conducting reliable testing even at a high temperature.
According to a first aspect of the present invention, a contactor is provided for testing electric characteristics of an object to be tested. This contactor includes: a contactor board; a plurality of conductive members formed through the contactor board; a plurality of beam members each having a tip and a base end at its both ends in which at least a conductive layer is provided between both ends and each beam member has a step between its tip and base end, which is connected to each conductive member; and a contact terminal member provided at the tip of each beam member in which the contact terminal member is formed integrally with the conductive layer of the beam member.
Preferably, the contact terminal member of this contactor is formed mainly of essentially the same material as the conductive layer of the beam member.
Preferably, the conductive layer of this contactor comprises one selected from the group consisting of nickel, copper, titanium, palladium, platinum, gold, tungsten, alloys of these metals, and metal compounds of these metals.
Preferably, the contact terminal member of this contactor is made of a high-hardness conductive metal, an alloy or metal compound thereof.
Preferably, the high-hardness conductive metal of this contactor is selected from titanium, tungsten, and alloys and metal compounds thereof.
According to a second aspect of the present invention, a method for manufacturing the contactor is provided. This manufacturing method, for forming the beam member and the contact terminal member of this contactor, comprises the steps of: forming a recess in a silicon substrate, the recess having such a cross section that deepens according to a pattern corresponding to a step shape of the beam member and being deepest at its bottom; forming a silicon layer on the recess; forming such a hole in the bottom that has a shape corresponding to the contact terminal member; and forming a film on the silicon layer and the side wall of the hole to constitute the conductive layer of the beam member and the contact terminal.
Preferably, the step of forming the silicon layer according to this method actually dopes boron.
Preferably, this manufacturing method further includes a step of directly joining the base end of the beam member to the conductive member of the contactor board.
Preferably, the joining by this manufacturing method comes in anode joining.
According to a third aspect of the present invention, a probe card is provided for testing the electric characteristics of an object to be tested. This probe card includes: a contactor according to the first aspect; a card board having a plurality of second conductive members arranged corresponding to the plurality of conductive members of the contactor; and an electric connection member interposed between the contactor and the card board. Of these components, the electric connection member serves to interconnect each of the conductive member of the contactor and each of the second conductive members of the card board.
Preferably, the electric connection member of this probe card has a cushioning structure.
Preferably, the electric connection member of this probe card is formed by a film forming process.
Preferably, the electric connection member of this probe card has an essentially xcexa9-shaped structure.
Preferably, the contactor board of this probe card is of an insulating nature.
Preferably, an elastic film is interposed between the contactor board and the card board of this probe card.
According to a fourth aspect of the present invention, a contactor is provided which is used to test electric characteristics of an object to be tested. This contactor includes: a contactor board; at least one conductive member formed through the contactor board; at least one beam member; and a contact terminal member provided at a tip of the beam member. Of these components, the beam member has one of a step shape and a slope shape and has its base end connected to the conductive member.
Preferably, the beam member of this contactor has a conductive layer formed thereon and its contact terminal member is formed integrally with the conductive layer of the beam member.
Preferably, the step-shaped beam member of this contactor is comprised of a plurality of step portions and a coupling portion for coupling them in such a configuration that at least one of the plurality of coupling portion couples in an inclined manner the two step portions disposed above and below it.
Preferably, the conductive member of this contactor is frusto-conical in shape in such a configuration that the base end of the beam member is connected to one of the two surfaces, whichever is larger in area.